A new process allows full recovery of starting materials from tough polymer composites.
In a groundbreaking development for materials science, innovators at the Department of Energy’s Oak Ridge National Laboratory (ORNL) have devised a closed-loop process for producing a resilient carbon-fibre-reinforced polymer (CFRP) while efficiently reclaiming all constituent materials.
CFRP, renowned for its lightweight, robust, and durable properties, holds immense potential for enhancing the performance and sustainability of various industries, including automotive, aerospace, and spacecraft manufacturing. However, traditional CFRPs pose significant recycling challenges, often ending up as single-use materials with substantial environmental footprints. ORNL’s closed-loop technology, detailed in a publication in Cell Reports Physical Science, represents a pivotal advancement in addressing this pressing sustainability issue.
Led by ORNL chemists Md Anisur Rahman and Tomonori Saito, alongside postdoctoral fellow Menisha Karunarathna Koralalage, the research team has developed a novel approach to CFRP synthesis that revolutionises conventional manufacturing paradigms.
Unlike traditional thermoset materials, which undergo irreversible crosslinking upon synthesis, ORNL’s innovative system introduces dynamic chemical groups into the polymer matrix and carbon fibres, enabling multiple reprocessing cycles without compromising mechanical properties such as strength and toughness.
The cornerstone of ORNL’s approach lies in the strategic incorporation of dynamic crosslinking, a process that imbues the CFRP with the ability to break and reform chemical bonds, facilitating seamless reprocessing and recycling. This dynamic bonding mechanism, combined with a robust interfacial adhesion between the polymer matrix and carbon fibres, yields a highly resilient composite material capable of withstanding diverse environmental stresses and mechanical loads.
A CIRCULAR ECONOMY
Central to the success of ORNL’s closed-loop system is its compatibility with circular economy principles, ensuring minimal material wastage and maximum resource efficiency. Through meticulous experimentation and optimisation, the research team has achieved a closed-loop recycling process wherein 100% of the starting materials – including the crosslinker, polymer, and fibres – are recovered and reincorporated into subsequent manufacturing cycles.
Beyond its sustainability credentials, the reversible crosslinked CFRP offers a host of additional benefits, including rapid thermosetting, self-adhesive properties, and the ability to repair microcracks within the composite matrix. Drawing inspiration from nature’s dynamic interfaces, such as nacre found in mollusk shells, the researchers have engineered a material that combines exceptional strength, resilience, and recyclability.
Looking ahead, the research team aims to explore the application of dynamic crosslinking in other composite materials, particularly glass-fibre composites, with the goal of expanding the technology’s reach across diverse industries.
By lowering costs and optimising performance, ORNL’s closed-loop CFRP technology holds the promise of revolutionising various sectors, from renewable energy and transportation to construction and consumer goods, ushering in a new era of sustainable manufacturing and resource utilisation.
